Solvent‐Dependent Divergent Cyclization of Bicyclo[1.1.0]butanes

Bicyclo[1.1.0]butanes (BCBs) have recently garnered significant research interest as versatile precursors for synthesizing potential [n.1.1] bioisosteres and multi‐functionalized cyclobutanes in a straightforward and atom‐economical manner. Here, we report a solvent‐dependent divergent cyclization of BCBs that providecs highly diastereospecific decorated cyclobutanes and oxygen‐containing bicyclo[3.1.1]heptanes (BCHeps), which serve as bioisosteres of meta‐substituted arenes. This novel strategy employs precision‐oriented control to achieve the desired divergence. Additionally, an unprecedented 1,2‐difunctionalization reaction mode for BCBs was explore, expanding the available methods for efficiently exploring the chemical space of arene bioisosteres and highly functionalized cyclobutanes.